Yield and Plant Growth Response of Peanut to Mid-Season Forage Harvest

Authors: Sorensen, Ronald - Ron; Nuti, Russell; Butts, Christopher - Chris

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2009
Publication Date: 10/15/2009
Citation: Sorensen, R.B., Nuti, R.C., Butts, C.L. 2009. Yield and Plant Growth Response of Peanut to Mid-Season Forage Harvest. Agronomy Journal. 101:1198-1203.

Interpretive Summary: Peanut is typically harvested for the nut which is used extensively for human consumption. The foliage byproduct is returned back to the soil as organic matter or baled, stored, and fed to cattle as a feed supplement. Previous research has shown that ‘Florigraze’ rhizoma peanut (Arachis glabrata, Benth.) forage had a crude protein of 12 to19%. This same study showed that palatability was excellent and the organic matter intake was 1.8 to 2.0 times the maintenance requirement for sheep. Other research showed that peanut residue may not supply significant amounts of nitrogen to the subsequent crop but could help increase organic matter content over time which could benefit soil characteristics. This implies that peanut residue may have an economic benefit to the grower as feed rather than for fertilizer. It may be possible to remove leaves mechanically to reduce disease incidence, increase row visibility at harvest, and provide an economic return to the grower by feeding or selling higher quality forage for livestock. There are currently no models relating loss of plant foliage to pod yield or grade especially when foliage is removed by mechanical means. Therefore the objectives of this research were to determine 1) total mass of foliage removed from the peanut crop, 2) yield and grade response of peanut to defoliation, and 3) the economic revenue with defoliation. The research site was installed on Tifton loamy sand with 2 to 5% slope. A Subsurface Drip Irrigation (SDI) system was installed in the spring of 2000 with drip laterals buried at 12 in deep and spaced at 3 ft with emitters spaced at 12 in. Peanut was planted following cotton at adjacent sites during the 2005 and 2006 growing seasons. Both cotton and peanut were managed for maximum yield following best management practice recommendations. The experiment was a randomized block design where peanut was defoliated at an 8 in height using a hedge trimmer at all combinations of control (uncut), 60, 90 and 120 days after planting with five replications per treatment. Leaf to stem ratio decreased as more cut periods occurred during the growing season. Pod yield, farmer stock grade and kernel size distribution were determined after being mechanically dried, weighed, and adjusted to 7% moisture (wet basis) and using screens specified in USDA grading procedures. At each defoliation time plant samples were collected and weighed from a 6ft by 3 ft (single cut) or 10 ft (multiple cut) area. An approximate 1.0 lb plant subsample was removed, weighed and dried to determine total dry mass (adjusted to 15% moisture). Another 1.0 lb plant sample was taken and separated into leaves and stems and weighed. A 0.10 lb subsample of leaves were weighed and passed through a leaf area meter (Li-Cor Biosciences Inc., www.licor.com) to determine leaf density. Leaf density was higher for peanut plants treated with Prohexadione Ca compared with those plants cut during the growing season. Forage mass was lowest when cut early in the season and increased with each single cut or with multiple cuts. The total mass removed for mid or late season single cuts were not significantly different than multiple cuts. Peanut pod yield decreased about 12% for each cut. Peanut farmer stock grade parameter TSMK decreased as the number of cuts increased, conversely, OK percent increased as the number of cuts increased. Pod revenue and forage revenue was highest for the uncut and single cut treatments and decreased as forage was removed with the multiple cuts. Two benefits of cutting peanut during the growing season would be: 1) to collect forage for animals, 2) increase revenue. These benefits are only valid if the forage removed are of high enough quality to promote excellent animal growth and the price per unit mass is high enough to cover expenses. More research is needed to determine peanut forage quality as an a

Technical Abstract: Defoliating peanut (Arachis hypogaea, L.) during mid-season may increase on-farm revenue through the sale of high quality peanut hay. It is unknown how the peanut plant will respond to defoliation with respect to plant characteristics, pod yield, farmer stock grade, and economic revenue. This experiment was a randomized block design where peanut was defoliated at a 20 cm height using a hedge trimmer at all combinations of control (uncut), plant growth regulator (uncut), 60, 90 and 120 days after planting. Prohexadione calcium (Ca salt of 3,5-dioxo-4-propionylcyclohexanecarboxylic acid) was applied two times at recommended rates and timing. There were a total of nine treatments replicated five times. Peanut (Georgia green) was planted in twin rows following cotton in 2005 and 2006 on a Tifton loamy sand (fine-loamy, kaolinitic, thermic Plinthic Kandiudults). Leaf to stem ratio decreased as more cut periods occurred during the growing season. Leaf density was higher for peanut plants treated with Prohexadione Ca compared with those plants cut during the growing season. Forage mass was lowest when cut early in the season and increased with each single cut or with multiple cuts. The total mass removed for mid or late season single cuts were not significantly different than multiple cuts. Peanut pod yield decreased about 12% for each cut. Peanut farmer stock grade parameter TSMK decreased as the number of cuts increased, conversely, OK percent increased as the number of cuts increased. Pod revenue and forage revenue was highest for the uncut and single cut treatments and decreased as forage was removed with the multiple cuts. Two benefits of cutting peanut during the growing season would be: 1) to collect forage for animals, 2) increase revenue. These benefits are only valid if the forage removed are of high enough quality to promote excellent animal growth and the price per unit mass is high enough to cover expenses. More research is needed to determine peanut forage quality as an animal feed supplement, soil characteristics following forage removal, and eventual farm economics.